This invention relates to improved seating structures of a type having portions which are shiftable in certain respects in correspondence with the movements of a user's body, to enhance the user's comfort.
Most conventional types of seat backs with which we are familiar have a tendency to become very uncomfortable after a user has been in the seat for any substantial period of time. This is true even in the case of upholstered type seats, which though cushioned for the purpose of providing a soft and yielding support to the user's back, are not capable of giving as effective support as would be desired when the user shifts his body slightly to different positions over a period of time. Further, many of these prior seats are, in any body position, very uncomfortable to the spine, by reason of their construction in a manner causing exertion of a substantial portion of the back supporting force directly against the bones of the spine, or by reason of their construction in such a non-supportive manner as to allow the spine to overly relax in a curved condition and rapidly develop fatigue.